Merge pull request #1958 from coder-zzzz/apache_bugfix/#1957_DefaultProducer_Timer_didn't_cancle

[ISSUE 1950] fix DefaultMQProducer didn't shutdown completely

client/src/main/java/org/apache/rocketmq/client/impl/producer/DefaultMQProducerImpl.java

@@ -258,7 +258,7 @@ public class DefaultMQProducerImpl implements MQProducerInner {
                 if (shutdownFactory) {
                     this.mQClientFactory.shutdown();
                 }
-
+                this.timer.cancel();
                 log.info("the producer [{}] shutdown OK", this.defaultMQProducer.getProducerGroup());
                 this.serviceState = ServiceState.SHUTDOWN_ALREADY;
                 break;